混凝土箱梁抗冻耐久性的无损检测研究

Non-Destructive Testing Study on the Frost Resistance Durability of Concrete Box Girder

针对现行规范中混凝土强度计算模型不适用于寒冷区域的问题,提出新的强度预测模型和无损检测标准,并通过实际工程进行验证。结果表明:寒冷地区混凝土实测强度要小于根据现行规范预测得出的强度,两者平均相对误差值达35.2%,而提出的寒冷区域混凝土强度预测模型平均预测误差值仅为3.41%,大幅降低了预测误差,预测效果更好;当冻融循环次数不断提高时,声波波速呈现阶梯状减小的趋势,混凝土抗压强度和回弹值都表现出逐渐降低的趋势。但抗压强度减小速度较慢,趋势较平缓。在混凝土中加入减水剂能很大程度抑制寒冷环境下混凝土强度的裂化趋势。本研究提出的无损检测寒冷区域混凝土箱梁抗冻耐久性方案,其各项参数和强度通过验证均达到了要求,能够大范围推广使用。

In response to the inadequacy of current specifications in calculating concrete strength for cold regions,a new strength prediction model and non-destructive testing standards are proposed and validated through practical engineering.The results indicate that the measured concrete strength in cold regions is lower than the strength predicted by existing specifications,with an average relative error of 35.2%.In contrast,the proposed concrete strength prediction model in the cold region shows an average prediction error of only 3.41%,significantly reducing the prediction error and demonstrating improved predictive accuracy.As the number of freeze-thaw cycles increases,the sonic wave velocity exhibits a stepwise decrease,and both compressive strength and rebound values of concrete show a gradual decline.However,the decrease in compressive strength is relatively slow and has a more gradual trend.The addition of water-reducing agent to concrete can effectively inhibit the cracking tendency of concrete strength in cold environments.The non-destructive testing scheme proposed in this study for the frost resistance and durability of concrete box girder in cold areas meets all requirements through validation of various parameters and strengths,making it suitable for widespread application.